Urea hydrolysis preheater

Abstract

The utility model relates to the technical field of preheaters, in particular to a urea hydrolysis preheater which comprises a shell, a feeding pipe arranged at the top of the shell, a discharging pipe arranged at the bottom of the shell, a heating assembly located in the shell, a mixing assembly and a flow divider. The heating assembly comprises a spiral heating pipe arranged on the inner wall of the shell in a surrounding mode and heat transfer cylinders arranged at intervals. The flow divider is communicated with the tail end of the feeding pipe, a plurality of spraying pipes are evenly distributed on the bottom face of the flow divider, the flow divider is used for evenly spraying a urea solution to different areas in the shell through the spraying pipes, and the urea solution conveyed by the feeding pipe can be evenly sprayed to the different areas in the shell through the spraying pipes. The urea solution is primarily and uniformly distributed when entering the preheater, so that the phenomenon that the local concentration is too high is reduced, and a good concentration environment is provided for subsequent hydrolysis reaction.

Description

Technical Field

[0001] This utility model relates to the field of preheater technology, and more specifically, to a urea hydrolysis preheater. Background Technology

[0002] In industrial production, urea hydrolysis preheaters are key equipment in the process of urea hydrolysis to generate ammonia, and are widely used, especially in environmental protection processes such as denitrification. However, existing urea hydrolysis preheaters have significant drawbacks: uneven mixing of the internal solution and large local concentration differences.

[0003] This is because the existing equipment has a simple feeding distribution structure, which can only achieve the initial introduction of the solution and cannot guarantee uniform spraying. At the same time, the heating and mixing components are poorly designed, which can easily lead to local overheating or insufficient heating during the heating process. In addition, the stirring structure has limited effect on disturbing the solution and cannot effectively break the concentration gradient.

[0004] The aforementioned problems lead to incomplete urea hydrolysis, low ammonia yield, and increased unreacted urea residue. This not only increases production costs but may also cause pipeline blockages, affecting the stability of subsequent processes. Therefore, there is an urgent need for a hydrolysis preheater that can achieve uniform distribution, efficient heating, and thorough mixing of the urea solution to solve the problems of uneven concentration and low reaction efficiency in existing technologies. Utility Model Content

[0005] The purpose of this invention is to provide a urea hydrolysis preheater. By distributing multiple layers of stirring blades along the axial direction of the rotating rod with adjacent layers tilting in opposite directions, the urea solution can generate a combined flow of up-and-down tumbling and horizontal shearing under the drive of a motor. This effectively breaks the local concentration gradient in the solution, achieving highly uniform mixing of the urea solution, thereby improving the yield and quality of ammonia. This invention addresses the problems of unreasonable design of heating and mixing components, which can easily lead to local overheating or insufficient heating during the heating process, and the limited disturbance effect of the stirring structure on the solution, making it difficult to effectively break the concentration gradient.

[0006] To achieve the above objectives, a urea hydrolysis preheater is provided, comprising a shell, a feed pipe disposed at the top of the shell, a discharge pipe disposed at the bottom of the shell, a heating component, a mixing component, and a distributor located inside the shell;

[0007] The heating assembly includes a spiral heating tube surrounding the inner wall of the housing and heat transfer cylinders spaced apart, the housing and heat transfer cylinders forming a heating cavity, and the spiral heating tube is located inside the heating cavity;

[0008] The distributor is connected to the end of the feed pipe, and multiple spray nozzles are evenly distributed on its bottom surface. The spray nozzles evenly spray the urea solution into different areas inside the shell.

[0009] The mixing assembly includes a vertically arranged rotating rod, multi-layered stirring blades mounted on the rotating rod, and a baffle plate fixed to the inner wall of the housing. A bracket is provided at the bottom of the housing, and a motor is fixedly connected to the top of the bracket. The output end of the motor is fixedly connected to the rotating rod through a coupling. A rotating shaft is rotatably connected to the end of the rotating rod, and the rotating shaft is fixedly connected to the bottom of the distributor.

[0010] As a further improvement to this technical solution, the housing includes a top plate, a bottom plate, and a cylindrical sidewall connecting the top plate and the bottom plate. Inspection ports are provided on the top plate and the bottom plate respectively, and the bottom of the housing is supported by support legs.

[0011] As a further improvement to this technical solution, the spiral heating tube is made of thermally conductive metal material, and its two ends are respectively connected to the inlet and outlet of an external heat source. The heat transfer cylinder is flat and fixed parallel to the inner wall of the shell, and is distributed at intervals with the spiral heating tube.

[0012] As a further improvement to this technical solution, the multi-layered stirring blades are evenly distributed along the axial direction of the rotating rod, and the inclination directions of adjacent two layers of stirring blades are opposite.

[0013] As a further improvement to this technical solution, the inner wall of the heat transfer cylinder is fixedly connected with multiple baffles, which are arc-shaped and used to disturb the urea solution flowing during the stirring process.

[0014] As a further improvement to this technical solution, the rotating shaft and the rotating rod are coaxially arranged, the top end of the rotating shaft is fixedly connected to the output shaft of the motor, and the bottom end is detachably connected to the rotating rod through a docking block.

[0015] As a further improvement to this technical solution, the bracket has an "L" shaped structure, with one end fixed to the bottom plate of the housing and the other end fixedly connected to the outer shell of the motor, for stable support of the motor.

[0016] Compared with the prior art, the beneficial effects of this utility model are as follows:

[0017] 1. In this urea hydrolysis preheater, the distributor evenly distributes the spray nozzles, which can evenly spray the urea solution conveyed by the feed pipe into different areas of the shell through multiple spray nozzles, so that the urea solution can be initially evenly distributed when it enters the preheater, reducing the phenomenon of excessively high local concentration and providing a good concentration environment for the subsequent hydrolysis reaction.

[0018] 2. In this urea hydrolysis preheater, a spiral heating tube is arranged around the inner wall of the shell. Its surface has a large contact area with the urea solution, which can more efficiently transfer the heat from the external heat source to the solution, uniformly increase the solution temperature, avoid local overheating or underheating, provide stable and suitable temperature conditions for the hydrolysis reaction, and promote the full progress of the reaction.

[0019] 3. In this urea hydrolysis preheater, multiple layers of stirring blades are distributed along the axial direction of the rotating rod, and adjacent layers are inclined in opposite directions. Driven by a motor, the urea solution can generate a composite flow of up-and-down tumbling and horizontal shearing. Meanwhile, the arc-shaped baffles distributed alternately on the inner wall of the shell further disturb the flowing solution. The two work together to effectively break the local concentration gradient in the solution, achieve highly uniform mixing of the urea solution, significantly improve the completeness of the hydrolysis reaction, and thus improve the yield and quality of ammonia. Attached Figure Description

[0020] Figure 1 This is a schematic diagram of the overall structure of this utility model;

[0021] Figure 2 This is a schematic diagram of the spiral heating tube of this utility model;

[0022] Figure 3 This is a cross-sectional view of the shell structure of this utility model;

[0023] Figure 4 This is a schematic diagram of the structure of the shunt of this utility model;

[0024] Figure 5 This is a schematic diagram of the structure of the stirring blade of this utility model.

[0025] In the diagram: 1. Shell; 2. Top plate; 3. Bottom plate; 4. Support leg; 5. Feed pipe; 6. Discharge pipe; 7. Heat transfer cylinder; 8. Spiral heating tube; 9. Diverter; 10. Nozzle; 11. Bracket; 12. Motor; 13. Rotating rod; 14. Connecting block; 15. Stirring blade; 16. Rotating shaft; 17. Baffle. Detailed Implementation

[0026] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present utility model. Obviously, the described embodiments are only some embodiments of the present utility model, and not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present utility model without creative effort are within the protection scope of the present utility model.

[0027] In the description of this utility model, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", etc., indicating the orientation or positional relationship are based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing this utility model and simplifying the description, and are not intended to indicate or imply that the device or component referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this utility model.

[0028] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this utility model, "a plurality of" means two or more, unless otherwise explicitly specified.

[0029] This utility model embodiment provides a urea hydrolysis preheater, which includes the following features:

[0030] For details, please refer to Figures 1-5 As shown, the device includes a housing 1, which is welded from a top plate 2, a bottom plate 3, and cylindrical sidewalls to form a closed reaction chamber that houses all core components. The inspection ports on the top plate 2 and bottom plate 3 are detachably connected by a sealing cover, providing direct maintenance access for internal components such as the spiral heating tube 8 and the stirring blade 15, avoiding the hassle of disassembling the entire device. Support legs 4 are vertically welded to the four corners of the bottom plate 3, elevating the housing 1 to a suitable operating height. This not only prevents the bottom from contacting corrosive substances from the ground, extending the equipment's lifespan, but also provides space for the discharge pipe 6, ensuring smooth discharge. The design of the support legs 4 and the inspection ports gives the equipment both stability and ease of use. Operators can quickly access the internal components through the upper and lower inspection ports, improving daily maintenance efficiency.

[0031] Please see Figures 3-4 The feed pipe 5 vertically penetrates the top plate 2, and its end is fixedly connected to the center inlet of the distributor 9 through a flange, which transports the external urea solution into the shell 1. The nozzles 10 evenly distributed on the bottom surface of the distributor 9 are connected to the internal cavity of the distributor 9, and the outlet faces the side wall and bottom of the shell 1. When the solution enters the distributor 9, the distributor 9 forces the concentrated liquid flow to diffuse radially, and it is divided into multiple fine streams through the nozzles 10, which are sprayed at a fan angle onto the inner wall and bottom area of ​​the shell 1.

[0032] The feed pipe 5 stably guides the solution vertically into the cavity, reducing flow resistance;

[0033] The flow divider 9 changes the direction of the liquid flow, from a single vertical flow to radial divergence;

[0034] The nozzle 10 refines the liquid flow, enabling uniform spraying at multiple points.

[0035] The combination of these three components ensures that the solution forms a uniform distribution covering the entire cross-sectional area when it enters the shell 1, avoiding the problem of excessively high concentration in the central region caused by traditional single-inlet feeding. This provides uniform initial concentration conditions for subsequent hydrolysis reactions and reduces the burden of stirring and mixing.

[0036] Please see Figures 2-3 The spiral heating tube 8 is made of thermally conductive metal material and spirals around the inner wall of the shell 1. Both ends are connected to an external heat source, such as a steam pipe, through flanges. The heat transfer cylinder 7 is a flat metal plate that is fixed parallel to the inner wall of the shell 1 and is distributed at intervals with the spiral heating tube 8. The spiral path of the spiral heating tube 8 extends the flow distance of the heat medium, realizing the circumferential heating of the solution and reducing the axial temperature gradient. The heat transfer cylinder 7 fills the gaps between the spiral heating tubes 8 and covers the heating blind area through planar heat conduction, thereby increasing the overall heat conduction area of ​​the inner wall of the shell 1.

[0037] The spiral heating tube 8 surrounds the heat exchanger and the heat transfer tube 7 conducts heat in a planar manner, forming a three-dimensional heat exchange network. This significantly improves the temperature uniformity of the solution during the heating process, avoiding incomplete urea decomposition or scaling problems caused by local overheating. The heat exchange efficiency is improved compared to the traditional straight tube heating structure.

[0038] Please see Figure 3 The motor 12 is fixed to the bottom of the base plate 3 via an "L"-shaped bracket 11. One end of the bracket 11 is welded to the edge of the top plate 2, and the other end is connected to the housing of the motor 12 by bolts, ensuring that the axis of the motor 12 coincides with the central axis of the housing 1. The top end of the rotating shaft 16 is keyed to the output shaft of the motor 12, and the bottom end is detachably connected to the rotating rod 13 via a mating block 14. The rotating rod 13 vertically penetrates the housing 1, and multiple layers of stirring blades 15 are fixed on it, with adjacent layers of blades tilting in opposite directions. The baffle 17 is an arc-shaped plate, which is fixed in an alternating manner. On the inner wall of the housing 1, the motor 12 and the bracket 11 provide stable power input, avoid eccentric vibration, and ensure long-term reliable operation of the stirring assembly; the rotating shaft 16 and the docking block 14 transmit power and realize quick disassembly and assembly of the stirring assembly. During maintenance, only the docking block 14 needs to be separated to remove the rotating rod 13; the multi-layer reverse design of the stirring blades 15 causes the solution to generate a composite flow of up-and-down tumbling and horizontal shearing, breaking the laminar flow state; the baffle 17 mechanically hinders the flow of the solution, changes the flow direction to form turbulence, and destroys the micro-concentration gradient.

[0039] Please see Figures 4-5The motor 12 drives the rotating shaft 16 to rotate the rotating rod 13. The stirring blade 15 pushes the solution to make a three-dimensional circulation flow. At the same time, the baffle 17 forms an asymmetric flow field on the inner wall of the shell 1. The two work together to quickly disperse the concentration gradient in the solution. The stirring blade 15 realizes macroscopic convection, and the baffle 17 enhances microscopic mixing, so that the urea particles are in full contact with heat, the hydrolysis reaction rate is increased, and the reaction completeness is significantly improved.

[0040] The discharge pipe 6 is located in the center of the base plate 3. The inlet is connected to the inside of the shell 1, and the outlet is connected to the subsequent processing pipe. Gravity is used to ensure that the hydrolyzed solution is discharged smoothly. The docking block 14 serves as the connection hub between the rotating shaft 16 and the rotating rod 13. The connection is detachable by bolts. During maintenance, the power component and the stirring component can be quickly separated, shortening the maintenance time.

[0041] The urea solution enters the distributor 9 through the feed pipe 5 and is evenly sprayed onto the inner wall and bottom of the shell 1 through the spray pipe 10 to form an initial uniform liquid layer, reducing local concentration differences from the source.

[0042] The spiral heating tube 8 provides heating, while the heat transfer cylinder 7 supplements the heat conduction. Together, they evenly transfer the heat from the external heat source to the solution, ensuring minimal temperature fluctuations during the heating process and providing a stable temperature environment for the hydrolysis reaction.

[0043] The motor 12 drives the rotating shaft 16 stably through the bracket 11, which in turn drives the rotating rod 13 and the multi-layer reverse stirring blades 15 to rotate. Together with the baffle 17 on the inner wall of the shell 1, it generates turbulence in the solution, quickly breaks the concentration gradient, and promotes the full hydrolysis of urea.

[0044] The hydrolyzed solution is discharged through the bottom discharge pipe 6, while the unreacted urea continues to mix and react in the turbulent flow. The nozzle 10 of the distributor 9 or the stirring blades 15 can be quickly cleaned or replaced through the inspection ports of the top plate 2 and the bottom plate 3, ensuring the long-term efficient operation of the equipment.

[0045] From the diversion and diffusion at the feed end to the three-dimensional heat conduction at the heating end, and then to the turbulence enhancement at the mixing end, each structure independently undertakes key functions such as the diverter 9 solving the initial distribution, the stirring blade 15 driving convection, and the baffle 17 refining the mixing, while forming an organic whole through spatial layout and connection design.

[0046] The feed pipe 5 introduces the urea solution into the distributor 9, which is then dispersed into multiple fine streams by the spray pipe 10 at the bottom of the distributor 9. These streams are evenly sprayed onto the inner wall and bottom of the shell 1. The combination of these three components ensures that the solution is evenly distributed upon entry, avoiding excessively high local concentrations in traditional single-inlet feeding and laying the foundation for subsequent processes.

[0047] A spiral heating tube 8 surrounds the inner wall of the shell 1 for heating, and a heat transfer cylinder 7 fills the gaps and supplements the heat conduction. The combination of the two forms a three-dimensional heat exchange, which allows heat to be evenly transferred to the solution, eliminates heating blind spots, and ensures that the hydrolysis reaction takes place at a stable temperature.

[0048] The motor 12 drives the rotating rod 13 and the multi-layer stirring blades 15 to rotate through the rotating shaft 16, causing the solution to tumble up and down and generate horizontal flow; the baffle 17 on the inner wall of the shell 1 disrupts the water flow and forms turbulence. The two work together to mix the solution from macroscopic to microscopic, break the concentration gradient, and promote the full hydrolysis of urea.

[0049] Support legs 4 suspend and stably support the housing 1, while the inspection ports on the top plate 2 and bottom plate 3 facilitate direct access to the internal components. This design ensures stable operation of the equipment and makes maintenance such as cleaning the distributor 9 and replacing the agitator blades 15 more convenient, improving usability.

[0050] Working principle: Urea solution enters the distributor 9 through the feed pipe 5 and is evenly sprayed onto the inner wall and bottom of the shell 1 through the spray pipe 10; the spiral heating pipe 8 surrounds the inner wall of the shell 1 for heating, and the heat transfer cylinder 7 is distributed at intervals to supplement the heat conduction. The heat from the external heat source is evenly transferred to the solution through the two; the motor 12 drives the rotating shaft 16 through the bracket 11, which drives the rotating rod 13 and the multi-layer counter-stirring blades 15 to rotate, and works with the baffle 17 on the inner wall of the shell 1 to generate turbulence in the solution; the hydrolyzed solution is discharged through the bottom discharge pipe 6, and the unreacted urea continues to mix in the turbulence; the spray pipe 10 of the distributor 9 or the stirring blades 15 can be cleaned or replaced through the inspection ports of the top plate 2 and the bottom plate 3.

[0051] The foregoing has shown and described the basic principles, main features, and advantages of this utility model. Those skilled in the art should understand that this utility model is not limited to the above embodiments. The embodiments and descriptions in the specification are merely preferred examples and are not intended to limit the utility model. Various changes and modifications can be made to this utility model without departing from its spirit and scope, and all such changes and modifications fall within the scope of the claimed utility model. The scope of protection of this utility model is defined by the appended claims and their equivalents.

Claims

1. A urea hydrolysis preheater, comprising a shell (1), a feed pipe (5) disposed at the top of the shell (1), a discharge pipe (6) disposed at the bottom of the shell (1), a heating assembly, a mixing assembly, and a distributor (9) located inside the shell (1); characterized in that: The heating assembly includes a spiral heating tube (8) surrounding the inner wall of the housing (1) and a heat transfer cylinder (7) spaced apart. The housing (1) and the heat transfer cylinder (7) form a heating cavity, and the spiral heating tube (8) is located inside the heating cavity. The distributor (9) is connected to the end of the feed pipe (5), and multiple nozzles (10) are evenly distributed on its bottom surface. The nozzles (10) spray urea solution evenly into different areas inside the shell (1). The mixing assembly includes a vertically arranged rotating rod (13), multi-layer stirring blades (15) mounted on the rotating rod (13), and a baffle plate (17) fixed to the inner wall of the housing (1). A bracket (11) is provided at the bottom of the housing (1), and a motor (12) is fixedly connected to the top of the bracket (11). The output end of the motor (12) is fixedly connected to the rotating rod (13) through a coupling. A rotating shaft (16) is rotatably connected to the end of the rotating rod (13), and the rotating shaft (16) is fixedly connected to the bottom of the distributor (9).

2. A urea hydrolysis preheater according to claim 1, characterized in that: The housing (1) includes a top plate (2), a bottom plate (3) and a cylindrical sidewall connecting the top plate (2) and the bottom plate (3). Inspection ports are provided on the top plate (2) and the bottom plate (3) respectively. The bottom of the housing (1) is supported by support legs (4).

3. A urea hydrolysis preheater according to claim 2, characterized in that: The spiral heating tube (8) is made of thermally conductive metal material, and its two ends are connected to the inlet and outlet of an external heat source respectively. The heat transfer cylinder (7) is flat and fixed parallel to the inner wall of the shell (1), and is distributed at intervals with the spiral heating tube (8).

4. A urea hydrolysis preheater according to claim 3, characterized in that: The multi-layered stirring blades (15) are evenly distributed along the axial direction of the rotating rod (13), and the inclination directions of adjacent two layers of stirring blades (15) are opposite.

5. A urea hydrolysis preheater according to claim 4, characterized in that: The inner wall of the heat transfer cylinder (7) is fixedly connected with multiple baffles (17), which are arc-shaped and used to disturb the urea solution flowing during the stirring process.

6. A urea hydrolysis preheater according to claim 1, characterized in that: The rotating shaft (16) is coaxially arranged with the rotating rod (13). The top end of the rotating shaft (16) is fixedly connected to the output shaft of the motor (12), and the bottom end is detachably connected to the rotating rod (13) through the docking block (14).

7. A urea hydrolysis preheater according to claim 1, characterized in that: The bracket (11) has an "L" shaped structure. One end is fixed to the bottom plate (3) of the housing (1), and the other end is fixedly connected to the outer shell of the motor (12) to stably support the motor (12).

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